In “conventional” farming operations, harvesting of crops typically results in crop harvest residue (e.g., corn stalks, leaves, tassles, etc.) being distributed somewhat randomly about the surface of a field. After the harvest, a farmer might use equipment such as a stalk chopper to shred the remaining standing stalks and residue. This would then typically be followed by a type of total coverage, deep-tillage pass with plowing equipment such as a moldboard plow, chisel plow, or a v-ripper plow, in order to tear up the soil profile and to incorporate the harvest residue into the soil. In the springtime, prior to planting the next crop, the farmer would again typically need to make one or two passes across the field with tillage tools, such as a field cultivator or disk, to prepare the soil surface to make a seed bed for planting. This harvest, post-harvest, and springtime pattern is essentially the state of the art for most conventional tillage cropping farms in operation today.
“No-till” farming is a term used to describe farming operations which are generally performed without any fall or spring tillage prior to planting. No-till planting equipment is generally equipped with a row cleaner to move the previous year's harvest residue out of the path of the row unit that places the seeds in the soil. No-till planters typically use a wavy coulter that operates at the approximate depth at which the seeds are planted. The waves on the coulter may provide some minimal tillage to allow the planter to operate in loosened soil. In many soil conditions, the coulter does not adequately loosen the dense soil that has not been previously tilled. Sidewall compaction may also result from pressing the soil sideways to form a slot to drop the seeds into. This may make it difficult to achieve good seed-to-soil contact. Poor seed germination and emergence, along with poor root development, are commonly-cited drawbacks of no-till operations, often caused by compacted soil with limited or poorly distributed pore spacing (to hold air and water). Improper pore size and distribution hinders air and water exchange, which may reduce water infiltration and utilization, and may thereby hamper healthy plant development.
“Strip-till” farming is a term that describes an emerging farming practice that has evolved from no-till farming, and can generally be described as tilling relatively narrow strips of soil between rows of the previous year's crop, and subsequently planting rows directly into the tilled strips with a planter row unit. Residue from the harvest (e.g., stalks, leaves, tassles, corn husks, etc.) is left as ground cover (as in no-till), and is distributed somewhat randomly following the harvest. In some operations, strip-tilling may be performed in the fall shortly following the harvest, with planting into the tilled strips occurring the following spring. This process is sometimes also referred to as “no-till with fall strip-tilling.” Strip-tilling can also be performed in the spring, prior to or in conjunction with planting, for example, by positioning strip-till equipment ahead of the planter units. In some operations, strip-tilling may be enhanced by the application of fertilizer, preferably (but not necessarily) at the same time as strip-tilling. Anhydrous ammonia, liquid and/or dry fertilizer can be placed into the tilled strips at the same time that the strip-tillage is being performed, for example.
Strip-tilling has been performed using conventional anhydrous ammonia applicators, which may use a coulter, a knife mounted to a shank, or a double disc sealer, for example, and may also use markers or Global Positioning Satellite machine guidance to till and/or layout the strips to be planted in the spring. The shanks, or knives, are typically placed on a toolbar with the same row width as on the planter. For example, if a farmer has an 8-row, 30 inch planter (e.g., for planting 8 rows spaced apart at 30 inch intervals), he might use an 8-row strip-tillage unit to till the strips 30 inches from center-to-center, for example.
One of the difficulties encountered during strip-tilling is that harvest residue can become tangled in strip-till equipment, which can increase the amount of time and resources expended in strip-tilling operations. Another difficulty is that strip-tilling, particularly in the presence of higher crop residues, may result in slower spring warm-up of the soil in the strip till zone (which could delay planting), and may also reduce the effective seed-to-soil contact (which is desired to obtain good germination and crop emergence).